1. Field of the Invention
This invention generally relates to electrical hot beverage brewers, such as electrical hot coffee brewers or hot tea brewers, and more particularly to such brewers in which hot water is passed through an ingredient within a brew basket to make a freshly brewed beverage.
2. Description of the Prior Art
Commercial sized hot beverage brewers of the type that pass hot water through a beverage ingredient such as ground coffee, instant coffee, tea leaves, instant tea, cocoa, etc. are well know. Examples are shown in U.S. Pat. Nos. issued to Zbigniew G. Lassota, 5,000,082 issued Mar. 19, 1991; 5,331,885 issued Jul. 26, 1994; 5,943,944 issued Aug. 31, 1999; 6,148,717 is issued Nov. 21, 2000; 6,571,685 issued Jun. 3, 2003; 6,845,704 issued Jul. 22, 2003; and 6,829,901 issued Dec. 14, 2004, and reference should be made to these patents with respect to any details concerning brewers of this type, all of which are hereby incorporated by reference.
In these brewers, the hot water is kept at a preselected temperature within a hot water chamber that is substantially larger than the quantity of beverage to be made during a single brew cycle, such a 0.5-2.5 gallons. Such hot water chambers may have a capacity of twenty gallons or more. One reason that the hot water chamber is so much larger than the batch size of beverage to be made during each brew cycle is to reduce the amount of temperature reduction that is caused when fresh cold water is introduced to the hot water chamber during a brew cycle. During a brew cycle, the amount of hot water that is taken from the hot water chamber to be passed to the brew basket is automatically replenished with cold water from a pressurized cold water source such as from a public water utility. By maximizing the ratio of the total quantity of hot water in the chamber to the batch amount of cold water that is introduced to the chamber during any one brew cycle, the recovery time of the hot water chamber required to reheat all the water to the desired preselected temperature before the next brew cycle can begin is minimized. The hot water chamber system is intentionally designed to have a large thermal inertia. Because of the large quantity of water that is maintained at the preselected temperature, the temperature cannot be quickly lower or raised.
Consequently, such brewers are generally set up to operate at only one single temperature that is generally selected to be the optimum temperature for brewing the particular beverage that is to be brewed. If the brewer is intended to be used as a tea brewer, then the set point for the hot water chamber temperature is fixed at the optimum temperature for tea, such as 160-degrees Fahrenheit. On the other hand, if the brewer is intended to be used to brew coffee, then the hot water chamber water temperature is selected to be the optimum brewing temperature for the particular type of coffee being brewed, such as 205-210-degrees Fahrenheit. Thus, during installation of a commercial brewer, the technician-installer programs the microprocessor based brewer controller to operate one or more heating elements within the hot water chamber to maintain the hot water at one and only one preselected optimum temperature for the intended type of beverage that is going to be brewed. This temperature remains fixed and generally the user or operator does not have access to the program for changing the set temperature.
If it is desired to change the setup of the brewer from coffee to tea or vice versa, then the trained technician-installer must make the change. In any event, there are no operator accessible controls to change the automatically maintained set temperature. If a change is made, then it may take several minutes or longer, depending upon the magnitude of the change, before the actual temperature of the hot water in the chamber is at the set temperature. Until then, the brewer is often disabled from performing another brew cycle. While the rate of change can be increased by increasing the size of the heating elements, as a practical matter, because of the large thermal inertia of the hot water chamber system, heaters large enough to rapidly change the temperature would draw more amperage than would normally be permitted by the AC power supplies of typical commercial users. Also, when it is desired to lower the temperature, the rate of lowering is dictated by ambient temperature and the heat loss characteristics of the hot water chamber which cannot be changed.
The large size of hot water chambers in known commercial brewers is not simply a matter of design choice but is required for successful operation. Successful operation in known single ingredient brewers requires the temperature to remain fixed and the quantity of hot water in the chamber to remain relatively stable. Generally, the hot water chamber in known brewers is intentionally designed to hold a quantity of hot water that is several times the quantity used during a single brew cycle to provide the chamber with a high level of thermal inertia. The high thermal inertia is needed so that the addition of cold water to the hot water chamber does not drastically lower the temperature of the hot water being drawn from the chamber during a brew cycle as cold water is added to the bottom of the chamber as hot water is drained off of the top of chamber. In known brewers, where quantity of dispense water is determined by measuring the length of elapsed time that a dispense valve is opened, a large hot water chamber is necessary to maintain a relatively fixed level so that the dispense rate remains relatively fixed despite the removal of hot water from the chamber during a brew cycle.
Because the circumstances relating to the size of the hot water chamber in commercial brewers, it is believed unknown in commercial brewers to selectively brew different types of beverage ingredients that have different optimum brewing temperatures by changing the brewing water temperature between successive brew cycles during normal operations. That is if it is desired to provide freshly brewed tea and freshly brewed coffee, two separate brewers must be used and the cost of space, operations, maintenance, etc. of two brewers must be absorbed.